Electrochemical Determination of Vitamin D ₃ in Pharmaceutical Products by Using Boron Doped Diamond Electrode

Abstract

Abstract A sensitive square‐wave voltammetry method was developed to determine cholecalciferol (vitamin D 3 ) in pharmaceutical products at boron‐doped diamond electrode as a working electrode. Vitamin D 3 provided a well‐defined voltammetric peak at around +1.00 V ( vs . Ag/AgCl, 3.5 mol dm −3 ) in 0.02 mol dm −3 Britton‐Robinson buffer pH 5.0 prepared in 50 % ethanol. The influence of various factors such as type and pH of the supporting electrolyte, scan rate and square‐wave parameters were studied and optimized. Under optimum conditions, the oxidation peak current increased linearly with the concentration of vitamin D 3 over the range of 2 to 200 μmol dm −3 . The calculated limit of detection and limit of quantitation were 0.17 μmol dm −3 and 0.51 μmol dm −3 , respectively. The boron‐doped diamond electrode exhibited specific recognition capability for cholecalciferol amongst possible interferences, and the determination of vitamin D 3 was possible in samples such as commercial pharmaceutical products without complicated sample pretreatments.